The present disclosure relates to processing of acoustic signals, and more particularly, to a microphone driving device and a digital microphone including the same.
Digital Micro Electro Mechanical Systems (MEMS) microphones include MEMS transducers and application specific integrated circuits (ASICs). The MEMS transducer includes a capacitor whose capacitance varies with a sound pressure change. The MEMS transducer transfers electrical signals generated by these capacitors to the ASIC. A typical ASIC amplifies the electrical signal received from the MEMS transducer at a specified rate. In this case, the amplification gain of the ASIC's amplifier depends on the maximum value of the input signal of an analog-to-digital converter.
Recent digital MEMS microphones are required to have a wide dynamic range by enabling high sound pressure signal processing of over 130 dBSPL. A digital MEMS microphone using an existing fixed amplification gain should apply a signal to an analog-to-digital converter within the maximum input signal range of the analog-to-digital converter. In this case, when a signal of a relatively low sound pressure is applied to the ASIC, the SNR characteristic deteriorates. Therefore, there is a demand for a microphone driving device for improving SNR characteristics while expanding the dynamic range of a digital microphone.